* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    padding: 40px;
    max-width: 500px;
    width: 100%;
}

h1 {
    text-align: center;
    color: #333;
    margin-bottom: 30px;
    font-size: 2.5em;
    font-weight: 300;
}

.canvas-container {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
}

#circleCanvas {
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    cursor: pointer;
    transition: border-color 0.3s ease;
}

#circleCanvas:hover {
    border-color: #667eea;
}

.controls {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

label {
    font-weight: 500;
    color: #555;
    font-size: 14px;
}

.slider {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: #e0e0e0;
    outline: none;
    transition: background 0.3s;
}

.slider:hover {
    background: #d0d0d0;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: #667eea;
    cursor: pointer;
    transition: background 0.3s;
}

.slider::-webkit-slider-thumb:hover {
    background: #5a6fd8;
}

.slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: #667eea;
    cursor: pointer;
    border: none;
}

.color-picker {
    width: 50px;
    height: 40px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.btn {
    background: #667eea;
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.3s;
    align-self: center;
}

.btn:hover {
    background: #5a6fd8;
}

.info {
    text-align: center;
    margin-top: 20px;
    color: #666;
    font-size: 14px;
}

.info p {
    margin: 0;
}

@media (max-width: 600px) {
    .container {
        padding: 20px;
    }
    
    h1 {
        font-size: 2em;
    }
    
    #circleCanvas {
        width: 100%;
        max-width: 300px;
        height: auto;
    }
}